1. Field of the Invention
This invention relates to a backpack type operating unit, more particularly to a backpack type operating unit having an operating device such as a chemical dispersion device, a blower or the like and a motive power source for driving the operating device such as an engine, both of which are mounted on a backpack frame.
2. Description of the Prior Art
One example of the conventional backpack type operating units having an operating device and an engine power is illustrated in U.S. Pat. No. 4,552,100, in which the operating unit is provided with an arm having a throttle lever on its end for operating the engine. This arm is pivotably supported on a support member which is secured to the left lateral side of the operating unit so that the arm can be pivoted on a vertical plane at the left lateral side of the operating unit. According to the conventional unit, when operating the operating unit, the arm is pivoted forward on the plane so as to point straight toward the forward direction of the unit. On the other hand, when the operating unit is housed, the arm is pivoted on the plane so as to point vertically and upwardly.
However, according to the conventional operating unit, when the arm points straight toward the forward direction of the unit, it extends along the side of an operator. As a result, the arm is liable to strike the body of the operator, depending on the type of operation and the physical characteristics of the operator, which results in the inconvenience during the operation of the unit.
To solve this problem, an improved operating unit as disclosed in Laid Open Japanese Utility Model Application No. 64-28972 has been proposed. In the proposed operating unit. A mounting surface of the arm is faced toward a direction inclined downwardly and rearwardly with respect to the leftward direction of the operating unit in such a manner that the arm is rotated on a plane inclined with respect to the vertical plane generated at the lateral side of the operating unit. As a result, when the arm is pivoted forward to the front pivotal position, it points toward a direction inclined leftwardly with respect to the forward direction of the operating unit, that is, it extends toward a direction far from the operator. So that the arm rarely contacts with the body of the operator during the operation.
However, in the proposed operating unit, the arm is inclined outwardly not only at the front pivotal position but also at the upper pivotal position. Namely, even when the arm is provided upwardly, it is inclined outwardly with respect to the operating unit. This means that when the arm is pivoted upward to the operating unit, the arm remains being outwardly protruded. Consequently, the arm is likely to be damaged if it comes into contact with surroundings. Therefore, this outward inclination of the arm at the upper pivotal position is undesirable. Further, since the mounting surface of the arm is faced toward the direction as described above, that is, downwardly and rearwardly, a process of manufacturing a die of the arm is complicated.